Summit Materials Announces 2030 and 2050 Climate and Inclusion Targets

Summit Materials, Inc. (NYSE: SUM, "Summit," or the "Company"), a leading vertically integrated construction materials company, today announced the publication of its 2021 Environmental, Social, and Governance Report and its inaugural Diversity, Equity, and Inclusion Report. These reports provide an update on the Company's progress toward its environmental, social, and governance initiatives and outline its updated long-term goals.

CEO of Summit Materials, Anne Noonan, commented, "Our three North Star Pillars of Human/Social Impact, Land Reclamation, and Carbon Reduction, and their associated targets, demonstrate Summit's commitment to becoming the most socially responsible construction materials provider and helping our communities in building a better and more sustainable future."

"We've made important progress this last year," said Anne, "and will continue to champion our three pillars across our businesses to contribute to meaningful change in our industry and communities."

As the world transitions to a lower-carbon future and customers and investors increasingly seek strong financial, operational and ESG performance, Summit's targets are designed to foster social responsibility, business resiliency, and value creation. The sustainability initiatives align with the company's three North Star Pillars developed through a strategic assessment as an integral part of its Elevate Summit Strategy.

Human/Social Impact:

With a dedicated focus on seeking to ensure employees and their communities are valued and can thrive, the Company is focused on increasing safety ownership and employee engagement, reducing employee turnover, and increasing diversity throughout its employee base. FY21 Highlights include:

• In 2021, our safety recordable incident rate improved by approximately 9% and our preventable vehicle incident rate improved by approximately 33% over 2020.
• Gender parity achieved at the Board and executive officer level.
• Committed to greater transparency and clarity around our Diversity, Equity, and Inclusion (DE&I) strategy, detailed in the reports published this month.
• Launched an employee stock purchase plan and companywide engagement survey ? a vital process to listen to and understand employees' needs.

Land Reclamation:

Summit Materials is committed to measuring every drop of water the Company consumes and returning land better than when Summit found it. FY21 progress includes:

• Received Wildlife Habitat Council (WHC) Gold Certification for the conservation program at its Davenport Cement plant, which was just named a finalist for the 2022 WHC Wetlands and Water Bodies Project Award.
• On-going installation of automated wash out systems at many of the company's ready-mix sites to manage water usage.
• Continued use and development of closed loop water systems to reduce freshwater withdrawn.
• Progressing a comprehensive, companywide reclamation policy in consultation with stakeholders, which Summit expects to publish in 2023.

Carbon Reduction:

Summit aims to become a leader in the industry by striving to reduce our carbon emissions by 25% in 2030 and reach net zero by 2050. FY21 highlights include:

• Reporting a 4% reduction in Global Scope 1 emissions relative to the Company's 2020 baseline.
• Piloting systems that inject recycled CO2 into fresh concrete to reduce its carbon footprint without compromising performance, and planning to install the systems at additional ready-mix locations in 2022.
• Leveraging telematics in all Summit-owned over the road vehicles to track fuel consumption and emissions.
• Launching project to convert generator-powered assets to line power to accelerate a longer-term transition to renewable power.
• Helping develop and then sign the Portland Cement Association's Roadmap to Carbon Neutrality.
• Completing the conversion of its Davenport plant to Portland Limestone Cement (PLC), which will help reduce carbon emissions in the production of cement.

"We are excited to make quantifiable 2030 and 2050 commitments to address climate change, land, and water use as well as diversity, equity, inclusion, and employee engagement goals at Summit Materials," said Karli Anderson, Chief Environmental, Social, and Governance Officer and Head of Investor Relations at Summit. "The progress we've made moving from assessing our impact, to creating targets and strategies to meet them, serves as a testament to our efforts to help build a more sustainable future. I believe what makes Summit unique is a dedication to social responsibility that permeates our business ? from many of our front-line leaders, to our mid-level managers, to our leadership team. This is just the beginning."

To learn more about the Summit's ESG success and specific long-term 2030 and 2050 targets, ESG initiatives, visit the Summit Materials Sustainability Page.

About Summit Materials

Summit Materials is a leading vertically integrated materials-based company that supplies aggregates, cement, ready-mix concrete and asphalt in the United States and British Columbia, Canada. Summit is a geographically diverse, materials-based business of scale that offers customers a single-source provider of construction materials and related downstream products in the public infrastructure, residential and nonresidential, and end markets. Summit has a strong track record of successful acquisitions since its founding and continues to pursue growth opportunities in new and existing markets. For more information about Summit Materials, please visit www.summit-materials.com.

Cautionary Statement Regarding Forward-Looking Statements

This press release contains "forward-looking statements" within the meaning of the federal securities laws, which involve risks and uncertainties. Forward-looking statements include all statements that do not relate solely to historical or current facts, and you can identify forward-looking statements because they contain words such as "believes," "expects," "may," "will," "should," "seeks," "intends," "trends," "plans," "estimates," "projects" or "anticipates" or similar expressions that concern our strategy, plans, expectations or intentions. These forward-looking statements are subject to risks, uncertainties and other factors that may cause our actual results, performance or achievements to be different from future results, performance or achievements expressed or implied by such forward-looking statements. We derive many of our forward-looking statements from our operating budgets and forecasts, which are based upon many detailed assumptions. While we believe that our assumptions are reasonable, it is very difficult to predict the effect of known factors, and, of course, it is impossible to anticipate all factors that could affect our actual results.

In light of the significant uncertainties inherent in the forward-looking statements included herein, the inclusion of such information should not be regarded as a representation by us or any other person that the results or conditions described in such statements or our objectives and plans will be realized. Important factors could affect our results and could cause results to differ materially from those expressed in our forward-looking statements, including but not limited to factors impacting the Company's inability to achieve its environmental, social and governance (ESG) targets within the projected timelines or in the projected manner, the inability to achieve its Diversity, Equity and Inclusion initiatives and targets within the projected timelines or in the projected manner, the inability to reduce turnover at the desired levels and within the desired timelines, the inability to achieve targeted employee engagement levels within desired timelines, the lack of economically viable market-based CO₂e offsets and credits, the performance of our environmental management system, the performance of existing technology related to CO₂e emission reductions, the development of future technologies related to CO₂e emissions, the continued evolution and development of ESG methodologies, frameworks and standards, market adoption of products with less environmental impact, including without limitation, Portland Limestone Cement, the ability to reduce turnover at the desired levels and within the desired timelines, and the factors discussed in the section entitled "Risk Factors" in Summit's Annual Report on Form 10-K for the fiscal year ended January 1, 2022 as filed with the Securities and Exchange Commission, as such may be updated by our subsequent filings. We undertake no obligation to publicly update or revise any forward-looking statement as a result of new information, future events or otherwise, except as required by law.